Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 1,091	$ 814
Prepaid expenses and other current assets	425	485
Total current assets	1,516	1,299
Restricted cash	71	71
Total assets	1,587	1,370
Current liabilities:
Accounts payable	3,573	2,856
Accrued expenses	3,527	3,129
Advance notes	950	807
Notes payable to vendors	1,546	1,471
Total current liabilities	9,596	8,263
Convertible notes	2,752	1,217
Total liabilities	12,348	9,480
Stockholders' deficit:
Common stock, $0.001 par value: 225,000,000 shares authorized at June 30, 2019 and December 31, 2018; 112,741,563 and 109,897,526 shares issued and outstanding at June 30, 2019 and December 31, 2018, respectively	113	110
Additional paid-in capital	269,606	266,381
Accumulated deficit	(280,480)	(274,601)
Total stockholders' deficit	(10,761)	(8,110)
Total liabilities and stockholders' deficit	$ 1,587	$ 1,370